730 EXPERIMENT STATION" EECOBD. [Vol.35 



ammonia and nitrate consuming power of certain soils ; and the effect of 

 dextrose and straw upon tliis consuming power. 



All the organisms were found capable of assimilating ammonia from ammo- 

 nium sulphate when dextrose was present as a source of energy. The presence 

 of dextrose was not found to inhibit the multiplication of organisms in casein 

 solution, but it did sometimes lessen the amount of casein decomposed. All the 

 bacteria experimented with in synthetic solutions containing dextrose and all 

 necessary plant food elements with ammonium sulphate as a source of nitrogen 

 successfully competed with maize seedlings for plant food elements when grown 

 in quartz sand containing 12 per cent moisture and maintained under conditions 

 that exclude other organisms. Under the conditions of the experiment the 

 difference observed in the growth of maize seedlings in the presence and the 

 absence of dextrose is attributed almost wholly to the competitive action of 

 the bacteria. The author claims that soils have a definite nitrogen and 

 ammonia consuming power and that when large quantities of straw are added 

 to the soil there is a marked decrease in tlie ammonifying power and a marked 

 increase in the ammonia and nitrate consuming power. Within certain limits 

 the number of bacteria and the ammonification of casein by B. mycoides is pro- 

 portional to the quantity of phosphorus or potassium added, when these ele- 

 ments are present in limited amounts. 



As a result of his investigations the author is led to believe that the so-called 

 ammonia-consuming power can not be used as an index of soil fertility. Molds 

 are considered to play an important part in the aerobic decomposition processes 

 of the soil, and they have been found active in the assimilation of plant food 

 constituents during the first stages of decomposition of crop residues and later 

 may play as important a part as bacteria in liberating plant food constituents. 

 Yeast and alg?e are also considered possible important factors in this regard. 



The scope and relations of tasonomic botany, A. S. Hitchcock {Science, 

 n. ser., ^3 (1916), No. 1106, pp. 331-3^2).— This is the address of the retiring 

 president of the Botanical Society of America delivered at Columbus, Ohio, on 

 December 29, 1915. 



Drug plants of North Dakota, Mae A. Englehorn (North Dakota Sta. Spec. 

 Bui., 4 (1916), No. 6, pp. 132-14S). — Descriptive lists are given of some drug 

 plants native to North Dakota, 21 of the species being recognized as official, 

 9 formerly so considered, and 39 unofficial drug plants which are thought to 

 have some therapeutic value. 



Notes on Quamasia with a description of a new species, C. V. Piper (Proc. 

 Biol. Soc. Wash., 29 (1916), pp. 711-81). — Notes are given on a number of species 

 of the genus Quamasia, and Q. walpolei n. sp. is described. 



Branching and flowering habits of cacao and patashte, O. F. Cook (TJ. S. 

 Nat. Mus., Contrib. Nat. Herbarium, 11 (1916), pt. 8, pp. IX +609-625, pis. 11).— 

 Results are given of field studies of the characters and habits of the cacao 

 tree (Theohroma cacao), together with the related food tree, Tribroma bicolor. 



The double stock, its history and behavior, Edith R. Saundek.s (Jour. Roy. 

 Sort. Soc, 40 (1915), No. 3, pp. 450-4112) .—This is a lecture delivered at the 

 meeting of the British Association for the Advancement of Science in Australia 

 in August, 1914. 



In giving more particular attention to the fact that the proportion of doubles 

 in a college garden at Cambridge was found to be far in excess of expecta- 

 tions, the author states that this appears from experiments to result ordinarily 

 from a process of unconscious selection by the gardener in favor of the plants 

 producing doubles by taking more forward and better grown plants to fill the 

 beds and discarding the rest. The strain is always kept going, the seed har- 



